1. Field of the Art
This invention relates to a reflection controllable view mirror device having an electro-optical means in which the optical transmittance changes in accordance with the voltage impressed thereon.
2. Description of the Prior Art
It has recently been contemplated to introduce a view mirror device of the type particularly for use in motor vehicles. The device has a flat mirror plate attached to one side of a liquid crystal pane, which acts as an electro-optical means, comprising a pair of opposed vitreous base plates each carrying a transparent electrode, and a liquid crystal encapsulated between the base plates.
Such is the construction that the panel transmittance varies with the change of voltage impressed across the electrodes. The varying transmittance controls the quantity of light passing through the panel to avoid an excessive amount of reflection from the panel to prevent glare.
The transmittance of the panel unavoidably undergoes changes because of dimensional deviations caused during the manufacturing process, because of the influence of the ambient temperatures, or because of deterioration from aging. These conditions render it difficult to maintain the transmittance constant as intended under the determined voltage and thus the present panels cannot provide effective glare prevention.